Sodium injection for advanced steam turbines

ABSTRACT

A novel, more sophisticated steam turbine design is proposed with reaction stages that have full admission, compounded by counter rotating axial blades, with impulse ignition utilizing sodium injection.

BACKGROUND OF THE INVENTION

There are two principal steam turbine types: reaction and impulse.

The impulse turbine has little or no pressure drop across its moving blades. Steam energy is transferred to the rotor entirely by the steam jets striking the moving blades. Since there is theoretically no pressure drop across the moving blades (and thus no reaction), internal clearances are large, and no balance piston is needed. These features make the impulse turbine a rugged and durable machine that can withstand the heavy-duty service of today's mechanical drive applications.

Today there is no pure impulse turbine. Manufacturers are using a combination of reaction and impulse design features to further improve turbine efficiency. The traditional impulse turbine manufacturers, who utilize the basic wheel and diaphragm construction, have been able to meet and many times exceed, the performance of a pure reaction turbine. This is done by adding a small amount of reaction to improve the performance, without the need for tight leakage controls or increasing thrust forces.

Steam turbine staging can vary:

-   -   i) Curtis staging—velocity compounded     -   ii) Rateau staging—pressure compounded

The most simple steam turbine configuration is the straight non-condensing design.

H₂O+Na→NaOH+H

Sodium reacts violently with water, and even with snow and ice, to give sodium hydroxide and hydrogen. The reaction liberates sufficient heat to melt the sodium and ignite the hydrogen.

Sodium hydroxide is perhaps the most important industrial alkali. Its major use is in the manufacture of chemicals, about 30% going into this category. The next major use is the manufacture of cellulose film and rayon, both of which proceed through soda cellulose (the reaction product of sodium hydroxide and cellulose); this accounts for about 25% of the total caustic soda production. Soap manufacture, petroleum refining, and pulp and paper manufacture each account for a little less than 10% of total sodium hydroxide uses. Sodium hydroxide; NaOH, is commonly known as caustic soda. It readily absorbs water from the atmosphere and must be protected in storage and handling. It is corrosive to the skin and must be handled with extreme care to avoid caustic burns.

Sodium ranks sixth in abundance among all of the elements in the Earth's crust, which contains 2.83% sodium in combined form. Only oxygen, silicon, aluminum, iron and calcium are more abundant. Sodium is after chlorine, the second most abundant element in solution in seawater.

SUMMARY OF THE INVENTION

A steam turbine design with reaction stages that have full admission, compounded by counter rotating axial blades, with impulse ignition utilizing sodium injection.

Reaction stages with full admission, compounded by counter rotating axial blades. Each propeller blade that is connected to the turbine axis is preceded by an impeller blade that is connected to the propeller blade with reverse gearing for counter rotation.

A sodium injection nozzle that is configured to inject elemental sodium into a steam turbine in such a way that the ignition of the hydrogen combustion cycle is prevented from returning through the nozzle. Thus the force of the combustion of the sodium with the steam entering the turbine is directed toward the turbine blades. Thereby increasing the pressure to force the turbine blades to turn with a greater RPM.

A conical plunger valve located at the orifice of the turbine where the steam enters the turbine. This valve is spring loaded to open in the repetitive combustion cycles within the turbine combustion chamber. The valve is made from Austenitic Stainless Steel type 316 L to be resistive to hydrogen embrittlement, and has a ceramic seat to withstand the higher combustive temperatures.

BRIEF DESCRIPTION OF THE DRAWING

The Drawing FIGURE depicts a cross sectional side view of the sodium injection steam turbine of the present invention and includes a detail of an exemplary impeller and counter rotating propeller engaged through a plurality of gears to effect the counter rotation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A thermal barrier coating on the interior of the turbine is recommended to include the turbine blades, to be able to withstand the higher temperatures of the hydrogen combustion cycle, from the exothermic reaction of the sodium with the water vapor. Boron nitride is suggested as a thermal barrier coating for this application.

As illustrated in the drawings a plunger valve is spring loaded to reopen after combustion of the hydrogen ignited by the sodium reaction with the water vapor. This plunger valve is located at the orifice of the turbine where the steam enters the turbine blade cavity, and is operative to prevent backflash travel of combustion to the steam source.

Sodium is injected into the steam turbine blade cavity with either a ball valve or other resistive closure mechanism to prevent the combustion cycle to backflash the sodium at its source. The sodium may be injected in a vapor, solid, or liquid phase.

The steam turbine blades are counter-rotating in series of two. An impeller precedes the propeller which is connected to the axial (shaft) of the steam turbine. These turbine blades are fully addressed, becoming larger in circumference from front to rear of the turbine. The purpose of the blades counter-rotating is to increase pressure and RPM on the axial shaft.

This steam turbine design can be used to turn a generator for power plant applications, and can also be used as an engine for vehicular transportation. 

1.) A conical plunger valve located at the orifice of the turbine where the steam enters the turbine. This valve is spring loaded to open in the repetitive combustion cycles within the turbine combustion chamber. The valve is made from Austenitic Stainless Steel type 316 L to be resistive to hydrogen embrittlement, and has a ceramic seat to withstand the higher combustive temperatures. 2.) A sodium injection nozzle that is configured to inject elemental sodium into a steam turbine in such a way that the ignition of the hydrogen combustion cycle is prevented from returning through the nozzle. Thus the force of the combustion of the sodium with the steam entering the turbine is directed toward the turbine blades. Thereby increasing the pressure to force the turbine blades to turn with a greater RPM. 3.) Reaction stages with full admission, compounded by counter rotating axial blades. Each propeller blade that is connected to the turbine axis is preceded by an impeller blade that is connecter to the propeller blade with reverse gearing for counter rotation. 